The subject matter disclosed herein relates to a steam turbine nozzle assembly, or diaphragm stage. Specifically, the subject matter disclosed herein relates to a steam turbine nozzle assembly including one or more flush holes (or, apertures) for flushing cavities within the nozzle assembly.
Steam turbines include static nozzle (or “airfoil”) segments that direct flow of a working fluid into turbine buckets connected to a rotating rotor. A complete assembly of nozzle segments is commonly referred to as a diaphragm stage, or nozzle assembly, of the steam turbine. Traditional nozzle assembly designs use a band-and-ring construction, while some modern approaches include nozzle segments having integral sidewalls bonded to rings. In either the traditional or modern approaches, cavities may exist between the band and ring, or nozzle sidewall and ring. These cavities may become contaminated, causing life-cycle and/or inefficiency issues in operation of the turbine. Additionally, removing contamination from cavities after operation (and before refurbishing and/or decommissioning) of a steam turbine, e.g., a nuclear steam turbine unit may difficult.